This invention relates to MOCVD deposition of interlayer metal conductors in integrated circuit fabrication, and specifically to a technique for providing superior adhesion of a copper thin film to a barrier metal.
The use of water in CVD of copper is known from Gelatos, et al, xe2x80x9cChemical vapor deposition of copper from Cu+1 precursors in the presence of water vaporxe2x80x9d, Appl. Phys. Lett. 63(20), 1993, pp. 2842-2844, wherein a method of adding water vapor to Cu(hfac)(tmvs), where hfac=hexafluoroacetylaceton and tmvs=trimethylvinylsilane, improves the deposition rate of copper and decrease the resistivity of the deposited copper thin films. Hochberg, et al., disclose a method of adding water to a Cu(hfac)(tmvs) precursor in the form of hexafluoroacetylacetone (hfac) dihydrate (H(hfac)(2H2O), in xe2x80x9cChemical Additives For Improved Copper CVD Processing Using (hfac)Cu(tmvs)xe2x80x9d, Advanced Metallization for ULSI Applications, 1994, wherein the stability of the precursor is improved and the deposition rate of copper thin films are increased, however, the conductivity of the copper thin films is not improved, and the formed copper thin films have a rough texture.
Jain, et al., xe2x80x9cChemical Vapor Deposition of Copper from (hfac)CuL (L=tmvs and 2-butyne) in the Presence of Water, Methanol and Dimethyl Etherxe2x80x9d, Chem. Mater., 8, pp 1119-1127, 1996, disclose a method of adding water vapor to (hfac)Cu(tmvs). The deposition rate of the copper precursor is improved, but the resistivity of the deposited copper is poor.
U.S. Pat. No. 5,744,192, granted Apr. 28, 1998 to Nguyen et al., for Method of using water vapor to increase the conductivity of cooper deposited with Cu(hfac) TMVS, describes a techniques of simultaneously injecting water and a copper precursor, wherein the water is vaporized into vaporized copper precursor prior to introduction of either the water or precursor into a CVD chamber. This is the currently method of injecting water along with copper precursor during CVD of copper films.
A method of chemical vapor deposition (CVD) of copper films includes preparing a substrate, including forming structures thereon have a barrier metal exposed surface; placing the prepared substrate into a CVD chamber; heating the substrate to a temperature of between about 200xc2x0 C. and 250xc2x0 C.; introducing a water flow in a carrier gas for at least one minute; stopping the water flow; and starting the flow of copper precursor.
An object of the invention is to provide a method of superior trench filling and step covering by copper films when deposited over barrier metals.
This summary and objectives of the invention are provided to enable quick comprehension of the nature of the invention. A more thorough understanding of the invention may be obtained by reference to the following detailed description of the preferred embodiment of the invention in connection with the drawings.